The invention relates to a device for guiding of air flow on vehicles, especially rear spoilers, with an air deflector which, in relation to the vehicle body, can be adjusted between a retracted position and an extended position, in which the air deflector, as a whole, is away from the vehicle body and, in relation to its orientation in retracted position, is inclined.
In a known device of this kind (FIG. 4 of German Offenlegungsschrift No. 28 51 639) the air deflector is supported by toggle joint arrangements, which are hinged in the area of the front end and in the area of the back end of the air deflector and which, optionally, can be folded out or in by drive means not explained more in detail there. The known device has many parts and is provided with at least six joints. An additional complication is that the adjustment movement of the toggle joint arrangement acting on the front end of the air deflector must be synchronized with the adjustment movement of the toggle joint arrangement working with the back end of the air deflector. The known device is expensive and vulnerable to failures. Moreover, because of the many joints there can be considerable bearing play.
Known devices (FIG. 3 of German Offenlegungsshrift No. 28 51 639, German Offenlegungsschrift No. 23 00 583, published European Application No. 0 153 743 and laid-open Japanese Application No. 60-92993) have a sturdier design, in which the adjustable air deflector is pivotally mounted, in a hinge-like manner, on the vehicle body or it can be displaced, by parallel guides, parallel to its initial position (DE-OS No. 26 49 953). But such a hinge-like pivoting or parallel adjustment frequently excludes, especially in the case of rear spoilers, an aerodynamically favorable position of the extended air deflector. Consequently, the effectiveness of the air deflector leaves much to be desired.
Thus, a primary object of the present invention is to provide a device with an adjustable air deflector, which is aerodynamically more favorable than devices with an air deflector that is displaceable by pivoting or parallel shifting on the vehicle body, but which, just the same, can be inexpensively produced with only a few moving parts, and which results in a favorable distribution of the acting forces and moments.
This object is achieved according to preferred embodiments of the invention in that the air deflector is supported by at least a curved adjuster that is rigidly connected to it, the adjuster being slidably guided in a correspondingly curved guide channel of a guide block that is fixed in relation to the vehicle body.
The invention is based on recognition of the fact that a passage of the air deflector from the retracted position into a desired fluidically favorable extended position can be achieved by an arcuate movement of the air deflector around an (imaginary) center of rotation based upon the two end positions of the air deflector, a center of rotation which corresponds to the center of curvature of the guide channel and of the adjuster and which, in the solution according to the invention, can be placed at any spot determined by the fluidic conditions. The device according to the invention requires only a few moving parts, so that, in a particularly simple way, a defined adjustment movement is provided for wherein bearing play can easily be kept small, and the force and moment distributions are favorable.
It is indeed known (German Patent No. 28 06 917) to provide an arcuate adjuster in the case of an adjustment device for a vent window of a vehicle, an adjuster which is slidably guided in a correspondingly arcuate guide channel of a guide block fastened to the vehicle body. But in this case, the vent window, on the end away from the adjuster, is connected to the vehicle body by hinges, which determine the swivel axis for the window, and the adjuster is hinged on the vent window.
The adjuster of the present invention can suitably be driven by an incompressible drive cable which, over at least a part of its length, can be laid in a guide pipe. In this case, advantageously, the end of the drive cable which is in driving connection with the adjuster can be slidably guided in an arcuate track formed in the guide block, whose center of curvature coincides with the center of curvature of the adjuster and of the guide channel. The sliding movement between the adjuster and the guide block takes place in an especially smooth way if the guide channel is defined by a series of flange-like webs within the guide block. Consequently, the friction between the guide block and adjuster is kept small. In a way that is particularly advantageous from a manufacturing and assembling engineering standpoint, the guide block can be formed by two half shells. The adjuster can be designed to be tubular. As a result, a very stable design of comparatively light weight can be achieved.
An annular seal is suitably placed at the location where the adjuster emerges from the guide block toward the air deflector, a seal which prevents the penetration of rain or wash water into the guide channel. In this connection, a particularly effective sealing is achieved if the opening of the annular seal, through which the adjuster axially extends, basically forms a continuation of the arcuate guide channel.
In accordance with another aspect of the invention, the air deflector is connected to a plate carried by the adjuster via screws. The plate is applied to the underside of the air deflector, and carries an extension which projects away from the air deflector into a facing end of the adjuster and is held there by means of a set screw. The set screw is screwed into the adjuster at a spot that is hidden within the guide channel when the air deflector is retracted. As a result, when the air deflector is retracted, its fastening elements are inaccessible. Theft of the air deflector is, therefore, effectively prevented. Preferably, in this case, the outer end of the screwed-in set screw is flush or almost flush with the outer surface of the adjuster. In this way, an unintentional loosening of the set screw is immediately recognizable by the fact that the air guide profile can no longer be brought into the retracted position. This contributes to increased security.
A threaded cable can be provided as a drive cable which meshes with a drive pinion of a drive unit. But in the interest of an increased continuous loadibility, the drive cable is preferably designed as wire rope, whose end away from the adjuster is connected to a rack which, on its part, meshes with the drive pinion of the drive unit. The drive unit can suitably comprise an electric motor which drives the drive pinion by a reduction gear set placed in a gear housing. When a drive cable in the form of awire rope with an attached rack is used, this rack advantageously is slidably guided in a guide channel of the gear housing and the rack, together with the gear housing, can form stops for limiting the range of movement of the air deflector, as a result of which the transmission of the impact forces to the drive cable is avoided. Instead of or in addition to such stops, mutually engageable stops can be provided on the adjuster and the guide block, in which case they would also prevent an unintentional withdrawal of the adjuster from the guide block.
Suitably, at least one limit switch, for producing a signal as a function of the adjustment movement of the air deflector, is provided which indicates whether the air deflector is in one of its end positions i.e., the retracted or extended position, or is in an inbetween position. By means of such a signal, in particular, the drive motor can be cut off. The limit switch can be mounted on the guide block and have a contact feeler projecting into the guide channel for the adjuster, while the adjuster, in the area facing the feeler, is provided with indentations or recesses into which the feeler can fall at spots which correspond to the end positions of the air deflector. But preferably, at least one limit switch is placed in a protected position within the gear housing and has contact feeler which projects into the guide channel for the rack and falls into a recess of the rack in the positions of the rack corresponding to the end positions of the air deflector.
In the interest of increased stability, the air deflector is preferably supported on at least two parallel adjusters which, in each case, are guided in their own guide block. The guide blocks in this case are advantageously fastened to a common base plate. Preferably, a drive unit serving for the common driving of the two adjusters is provided, which can also be fastened to the base plate. To be able to adjust the air deflector, even in the case of a failure of the drive motor, for example, because of a lack of on-board voltage, it is preferable to provide an emergency device for adjustment of the air deflector by hand after uncoupling of the electric motor and the reduction gear set. In this connection, a particularly simple and sturdy arrangement is obtained if the reduction gear set has a manually rotatable and axially shiftable drive shaft which is always in driving connection with the drive pinion for the drive cable but which, by axial sliding, can selectively be engaged or disengaged with the output side of the reduction gear set.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.